Fetch content based on XML content validation in bash

Question

I have an XML as follows

<demos>
 <demo>
  <a>00</a>
  <b>First</b>
  <c>ProjectA</c>
 </demo>
 <demo>
  <a>01</a>
  <b>Second</b>
  <c>ProjectB</c>
 </demo>
</demos>

Example 1: If within <a> tag has 00 and <c> tag has ProjectA, Output should be First

Example 2: If within <a> tag has 01 and <c> tag has ProjectB, Output should be Second

I want try with xml_grep or xpath as these are installed packages in linux by default. I tried different ways such as

xpath xtest.xml '//a[text()="01"]/text() | //b'

but this validation doesnt work.

Both `If` conditions in your question are true for the sample XML. What should be the output? — Tomalak, Mar 02 '18 at 09:05
Are you asking about how to select a sibling? https://stackoverflow.com/questions/17040254/how-to-select-a-node-using-xpath-if-sibling-node-has-a-specific-value — Micha Wiedenmann, Mar 02 '18 at 09:19
You should probably drop the [linux], [bash] and [shell] tags, imho this is an xpath question. — Micha Wiedenmann, Mar 02 '18 at 09:19
Which kind of command **xpath** do you have? On my system, I would have to run: `xpath -e '//a[text()="01"]/text() | //b' xtest.xml` instead. — Pierre François, Mar 02 '18 at 09:55

score 1 · Accepted Answer · answered Mar 02 '18 at 09:47

For example 1, you will have to run:

xpath -q -e '//demo[(a/text()="00") and (c/text()="ProjectA")]/b/text()' xtest.xml

For example 2:

xpath -q -e '//demo[(a/text()="01") and (c/text()="ProjectB")]/b/text()' xtest.xml

Be aware that xpath is not installed by default on any Linux. On Ubuntu, you will first have to run sudo apt install libxml-xpath-perl.

score 0 · Answer 2 · answered Mar 02 '18 at 09:40

0

The following command worked with XML as file.xml

 xpath file.xml '//demo[a/text()="00" and c/text()="ProjectA"]/b/text()'

answered Mar 02 '18 at 09:40

stackover flow

This doesn't work on Ubuntu with **xpath** installed along with **libxml-xpath-perl**. Probably, you have another flavour of xpath. – Pierre François Mar 02 '18 at 09:49
This is suse linux – stackover flow Mar 02 '18 at 10:07

score 0 · Answer 3 · answered Mar 02 '18 at 09:42

Robust xmlstarlet solution:

xmlstarlet sel -t -m '//demo/a' --if '. = 00 and ./following-sibling::c="ProjectA"' \
-v './following-sibling::b' -n input.xml

The output:

First

xmlstarlet sel -t -m '//demo/a' --if '. = 01 and ./following-sibling::c="ProjectB"' \
-v './following-sibling::b' -n input.xml

The output:

Second

3 Answers3